<?php
/*
 *  $Id$
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * This software consists of voluntary contributions made by many individuals
 * and is licensed under the LGPL. For more information, see
 * <http://www.doctrine-project.org>.
 */

/**
 * Doctrine_Pager_Range_Sliding
 *
 * @author      Guilherme Blanco <guilhermeblanco@hotmail.com>
 * @package     Doctrine
 * @subpackage  Pager
 * @license     http://www.opensource.org/licenses/lgpl-license.php LGPL
 * @version     $Revision$
 * @link        www.doctrine-project.org
 * @since       0.9
 */
class Doctrine_Pager_Range_Sliding extends Doctrine_Pager_Range
{
	/**
	 * @var int $_chunkLength     Chunk length to be returned
	 */
	private $_chunkLength;

	/**
	 * _initialize
	 *
	 * Initialize Doctrine_Pager_Range_Sliding and does custom assignments
	 *
	 * @return void
	 */
	protected function _initialize()
	{
		if (isset($this->_options['chunk'])) {
			$this->_setChunkLength($this->_options['chunk']);
		} else {
			throw new Doctrine_Pager_Exception('Missing parameter \'chunk\' that must be defined in options.');
		}
	}

	/**
	 * getChunkLength
	 *
	 * Returns the size of the chunk defined
	 *
	 * @return int        Chunk length
	 */
	public function getChunkLength()
	{
		return $this->_chunkLength;
	}

	/**
	 * _setChunkLength
	 *
	 * Defines the size of the chunk
	 *
	 * @param $chunkLength       Chunk length
	 * @return void
	 */
	protected function _setChunkLength($chunkLength)
	{
		$chunkLength = (int) $chunkLength;
		if ( !$chunkLength) {
			$chunkLength = 1;
		} else {
			$this->_chunkLength = $chunkLength;
		}
	}

	/**
	 * rangeAroundPage
	 *
	 * Calculate and returns an array representing the range around the current page
	 *
	 * @return array
	 */
	public function rangeAroundPage()
	{
		$pager = $this->getPager();

		if ($pager->getExecuted()) {
			$page  = $pager->getPage();
			$pages = $pager->getLastPage();

			$chunk = $this->getChunkLength();

			if ($chunk > $pages) {
				$chunk = $pages;
			}

			$chunkStart = $page - (floor($chunk / 2));
			$chunkEnd   = $page + (ceil($chunk / 2)-1);

			if ($chunkStart < 1) {
				$adjust = 1 - $chunkStart;
				$chunkStart = 1;
				$chunkEnd = $chunkEnd + $adjust;
			}

			if ($chunkEnd > $pages) {
				$adjust = $chunkEnd - $pages;
				$chunkStart = $chunkStart - $adjust;
				$chunkEnd = $pages;
			}

			return range($chunkStart, $chunkEnd);
		}

		throw new Doctrine_Pager_Exception(
            'Cannot retrieve the range around the page of a not yet executed Pager query'
            );
	}
}